There is a great deal of human and animal research showing how intermittent fasting can help you:
- Lose fat while maintaining lean muscle
- Boost metabolism
- Improve insulin-sensitivity and reduce the risk of developing diabetes
- Increase autophagy to reduce inflammation, decrease disease risk, and increase longevity
- Increase ketone production to protect the brain, improve learning and memory, and increase athletic performance
You’ve probably seen a similar list of benefits with other fads like cleanses, the HCG diet, the raw food diet, etc. That is quickly becoming a problem with intermittent fasting. Mixed in with all the peer-reviewed studies are tons of false claims, hyperbole, and over-exaggerations that are pushing it towards fitness fad. I see plenty of claims about how you can binge eat whatever you want, fast a few extra days a week and actually lose weight. Fasting isn’t magical. It does provide the benefits I listed above, but it does it by reducing your calorie intake. It’s just like any other weight loss solution in that calorie reduction is the goal, but it’s gaining in popularity and helping millions lose body fat because when it’s done correctly, it makes sticking to a healthy diet feel easier than continuous calorie reduction.
It also doesn’t seem to slow your metabolism like a standard long-term calorie restriction tends to do. And as I’ve mentioned previously fasting is necessary to trigger an important clean up process in the body known as autophagy that recycles old and damaged cells, cell organelles, and protein aggregates that build up and cause disease, inflammation, and dysfunction.
It’s not about willpower
Ultimately, the point of any diet fad is it promises to help you get your calories under control without making you feel miserable and deprived. This unfortunately, is where intermittent fasting is falling into the fad category. I see plenty of people talk about the benefits of fasting 2 days and eating 5 or fasting 16 hours and only eating for 8, but they don’t explain how to get there. They just explain the benefits and you will get there by willpower alone. It’s like explaining the benefits of running a marathon and then telling you the distance you need to cover for it to count as a race.
You can’t just hop into a marathon and hope to succeed and attempting to do the same with intermittent fasting will come to a similar disappointing end. Both exercise and fasting help strengthen the body because they both work similar energy-expenditure systems, and those systems need time and a progressive schedule of stressors to force them to adjust.
Stress and strengthen
I’m going to continue the exercise analogy because approaching intermittent fasting with a similar mindset will give you a much better chance at success. Also as with exercise, you’ll get the best results if you work towards a fasting schedule that you can maintain for the rest of your life. Fasting is a stressor that causes your body to adapt and improve, and just like with exercise, you need to take it slow and allow your body time to progress before moving on to greater challenges.
As with exercise, it will also be more uncomfortable at first than it will be later when your body is better adapted. Most people actually eat within a 15-hour window each day. Reducing that down to 12 or even 8 hours will take some adjustment, but it can be done. What may seem unthinkable today will eventually be second-nature 6 months later. You can expect to be a bit more hungry at first as you break old habits and eat less often than before, but taking it a step at a time will make it a much easier challenge to conquer.
Eating all the time makes your body incredibly poor at mobilizing fat from fat cells and burning it for fuel. Using body fat for fuel takes energy and your body won’t resort to this pathway at all if you’re continuously providing it with readily digested food. Just as your body won’t go through the effort of building muscles unless you force it to with exercise, your body isn’t going to activate genes, enzymes and hormones that help it utilize fat unless you force it to with progressive fasting.
Below are some suggestions to help you build up to a daily intermittent fasting schedule. You can adopt some or all of the suggestions depending on what works best for your preferences and lifestyle. An important point to clarify is that these tips lean heavily on the concept of time restricted eating. I’ve written about it previously here and it’s worth reading so you can understand how we evolved to eat during the day and fast at night. Trying to go against this pattern has been shown to cause fat gain, increase your preference for unhealthy foods, worsen sleep quality, and increase your risks for diseases like diabetes and cancer. For people that work at night and sleep during the day, intermittent fasting has been shown to counter the adverse effects of shift work so it’s still worth trying to adopt. Some of these tips may not apply directly if you’re a shift worker, but in general the best practice is try to structure your meals so you’re eating more when the sun is up and less when it isn’t.
Each step builds off of the last one, but many can be done in tandem if you’re feeling up to it. I also didn’t give a timeframe on how long to do each step because everyone varies and there is no perfect progression. Push yourself when you feel you can and slide back when needed and try again later. From losing weight to quitting smoking, we learn as much from our failures as we do our successes. Each step backwards is not the end, just a rest break as you get ready to try again.
1. Workout in the Morning Fasted: Before you try to reduce your eating window, start changing your epigenetics. Epigenetics is your body’s ability to turn genes on or off in response to environmental stimuli. In this case, you should do some kind of cardio training like walking, first thing in the morning (or whenever you wake up) on an empty stomach. Studies have shown that fasted training activates fat burning genes to help you better utilize stored fat for fuel. We eat too much sugar in our modern world and this continuous supply of carbohydrates damages your body’s ability to use stored fat for fuel. This not only reduces your aerobic capacity (every little bit of fuel helps), but it makes fasting much more difficult than it needs to be. You can eat after you finish, but you need to get used to the concept of moving without an external supply of energy first.
2. Start Increasing Fiber at Dinner: As I said before, intermittent fasting is not magical. Like with any diet, healthy fats, protein and fiber will fill you up and keep your appetite under control for hours afterwards. Low quality foods filled with processed carbohydrates quickly spike your appetite again and test your willpower. Fiber in particular has been shown to improve your sleep quality which will be important later on as you try to push back the boundaries of your fasting window. Willpower is highly reliant on sleep and a lack of sleep will make it much harder to stick to your plan at night. Half your dinner plate should be composed of vegetables. Limit simple sugars and saturated fats (keep the meat, just trim the fat) because these have also been shown to negatively impact sleep quality.
3. Pick 5 Continuous Fasting Days: Researchers from the Salk Institute have been studying the effects of circadian rhythms on metabolism, gene expression and the immune system for years. They have discovered how restricting your eating to the day and fasting at night protects against obesity, diabetes and cancer. They also discovered that you don’t need to do it continuously to reap the benefits. They found that the benefits of the time-restricted schedule was not harmed by the two-day “cheat weekend.” The researchers concluded that “the weekday time restricted feeding imprints a gene expression signature that can resist occasional changes in the feeding pattern.” It’s helpful to realize you can start with a little flexibility and not undo your efforts. Pick a schedule and start establishing your habit.
4. Stop Eating After Dinner: Once you’ve gotten used to filling meals that sustain you for hours afterwards, make it a point to stop eating completely after dinner. Late night eating itself impacts your circadian rhythms and causes you to prefer junk food. Simply avoiding an after-dinner snack makes you far less likely to want one the next night. It can take a week to break the post-dinner snacking habit, but you’ll quickly see it’s not hunger that drove that behavior, just routine. At this point, we’re not concerned about what time you eat dinner. You can push it back a little if you’re having difficulties making it all the way to bedtime without an additional meal.
5. Start Eating BreakFast Later: People have varying degrees of difficulty with this one. Some people hate breakfast and are glad to hear the science finally says it’s OK to skip it. Others use breakfast or coffee as part of their morning ritual to really wake them up. I’m afraid even those that like black coffee are going to need to push back the time they have that first cup. Time restricted eating centers around managing your circadian clock and the clock starts as soon as you consume anything more than water. Even black coffee counts because it activates the clock in your liver to metabolize the caffeine. The goal is to reduce your eating window so work on reducing it from both sides (morning and night) until you find the times that work best for you.
6. Aim for 13: You’ve already pushed back the borders on your fasting window, and now it’s time to start setting consistent, daily fasting goals. You won’t see too many intermittent fasting articles talking about a 13-hour fast as a goal, but it has been shown to provide health benefits. One interesting study found that women in remission for breast cancer reduced the likelihood of recurrence by 40 percent simply by fasting from 7 PM to 8 AM. This is significant because recurrence is incredibly common, and yet they were able to cut their risk significantly with this pretty easy to follow habit. It demonstrates the improvements taking place inside the body and is an important first step towards better health and longevity.
7. Start Eating Dinner Earlier: We weren’t concerned about the time of your dinner before. Now we are. Start moving it to earlier in the evening. It really is best for sleep quality and metabolic health to eat your last meal when the sun is up (or setting). It just better matches what we evolved to do. You’ll notice better sleep, better digestion, and improved energy the next day. You’ll also really notice the opposite when you break the habit.
8. Lose a Cheat Day: You may start to notice that your later-night cheat meals are becoming more unpleasant. You may feel more sluggish and miserable after a meal, get heartburn, etc. Pick one of the cheat days and lose it. You’ll be surprised how easy it is to add your eating schedule to another day of the week.
9. Aim for 16 to get 15: 15 is another important number. Studies have found that fasting for this length of time each night can double your time to exhaustion during cardio. It does this by increasing your body’s ability to produce ketones. In terms of fat loss, this means fat is being turned into usable fuel that actually can’t be stored again if it doesn’t get used (you just pee it out). In terms of health, ketones have been shown to reduce inflammation and improve brain health and function. Fasting for 15 hours also increases lean muscle mass as it cuts body fat. Your muscle develops because more of the fat inside the tissue is lost. You were previously marbled like a fatty steak and intermittent fasting helps you remove it, which improves muscle development. This is also true in organs like the liver that develop harmful fat deposits from overeating. In the studies at the Salk institute, they didn’t see increased benefit from going more than 15 hours a night, but other studies in mice showed that reducing the eating window all the way down to 3 hours (basically one meal) provided the greatest benefits to longevity. 16 hours is a standard intermittent fasting goal you’ll hear about frequently, but it’s not really any better than 15. However, I find aiming for 16 is a great way to get into the habit of successfully hitting the 15-hour fasting window each day.
10. Lose the Last Cheat Day: This is another point of preference that you can adopt or skip entirely. If you’re the type that really needs a cheat day to look forward to, it’s OK to keep it. In general, I find cheat days open the possibility of backsliding into old habits. Fitness is all about momentum. It takes a lot of effort to get the ball rolling, but once it’s going it takes much less effort to keep it going (and to keep you on track). A cheat day may be a beneficial psychological outlet for you or it might be a speed bump that could possibly slow your momentum. That’s for you to decide. It’s still fine to have an unscheduled cheat here and there even if you do get rid of the scheduled cheat day. The changes to your gene expression will prevent it from doing too much harm and you’ll find it easy to get right back to it the next day.
11. Experiment: Consider this the completion of your 5K-equivalent fasting training program. Your body is now adapted enough to successfully try other fasting regimens. Maybe 5:2 will work for you, or the Warrior Diet where you cut it down to one meal a day. You may even consider a prolonged fast like the fasting mimicking diet to significantly increase autophagy throughout your body, reduce your disease risk, and increase your longevity. Those are the bigger “events” and will be more taxing, but you’ve established the groundwork in your body to handle them. Feel free to try them out and see what helps and what’s hype.